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Environmental consciousness and tightening emissions legislation push the market share of electronic fuel injection within a dynamically growing world wide small engines market. Similar to automotive engines during late 1980's, this opens up opportunities for original equipment manufacturers (OEM) and suppliers to jointly advance small engines performance in terms of fuel economy, emissions, and drivability. In this context, advanced combustion system analyses from automotive engine testing have been applied to a typical production motorcycle small engine. The 125cc 4-stroke, 2-valve, air-cooled, single-cylinder engine with closed-loop lambda-controlled electronic port fuel injection was investigated in original series configuration on an engine dynamometer. The test cycle fuel consumption simulation provides reasonable best case fuel economy estimates based on stationary map fuel consumption measurements.

When developing diesel exhaust aftertreatment systems the often constrained packaging envelope is a challenge. In addition, the stringent emission legislation can necessitate the injection of additives, for example urea and/or hydrocarbons, to achieve performance targets. In such cases, a good distribution of reactants over the catalyst surface is beneficial but might be difficult to achieve. The uniformity of these distributions is often studied separately using a non-dimensional measure denoted as the Uniformity Index (UI). However, a combination of the exhaust gas UI and the UI for the additive is also interesting to study. In this work the origin, applicability and advantages of the uniformity index is discussed as a guide for developing diesel exhaust aftertreatment systems. Moreover, a matching index (UIα) is proposed for the analysis of systems where additives are injected. It is found that two skew distributions can give a good conversion if the profiles match.

Experience from more than 16000 Continuously-Regenerating Trap Systems (CRT®) fitted to city buses over an eight-year period is described. The widespread adoption of particulate filters for diesel buses in European cities has been due to their high effectiveness in emissions reduction, but has depended on the relative simplicity of fitting a device that does not usually need interconnection with the engine controls. In conditions giving good passive regeneration (particulate oxidation by NO2 under the normal exhaust conditions), the inherent durability is excellent. Almost all failures have been due too much soot accumulating in the traps, few of which yet have active regeneration systems. Such failures are usually spasmodic, and often due to high smoke from faulty engines, but a few bus fleets have suffered serious failure frequencies. These problems have been investigated and cured.

The tightening of Heavy Duty Diesel (HDD) emissions legislation throughout the world is leading to the development of emission control devices to enable HDD engines to meet the new standards. NOx and Particulate Matter (PM) are the key pollutants which these emission control systems need to address. Diesel Particulate Filters (DPFs) are already in use in significant numbers to control PM emissions from HDD vehicles, and Selective Catalytic Reduction (SCR) is a very promising technology to control NOx emissions. This paper describes the development and performance of the Compact SCR-Trap system - a pollution control device comprising a DPF-based system (the Continuously Regenerating Trap system) upstream of an SCR system. The system has been designed to be as easy to package as possible, by minimising the total volume of the system and by incorporating the SCR catalysts on annular substrates placed around the outside of the DPF-based system.

The reduction of particulate emissions is of major interest, especially in urban areas. The technology associated with particulate traps has been under development for more than twenty years, however past experiences have tended to show that regeneration systems are expensive and often suffer from durability problems. In this paper we report on an alternative approach in which a continuous low-temperature chemical reaction mechanism is employed. The system based on this technology consists of a special oxidation catalyst upstream of a particulate trap. Over the catalyst some of the engine-out NO emission is oxidised to NO2. NO2 is active for the continuous oxidation of soot collected in the trap above about 250 °C. As a result of this regeneration process the trap is always very lightly loaded with soot and the back-pressure level is therefore very low. The oxidation catalyst naturally also leads to very low emissions of CO and hydrocarbons.

The retrofitting of diesel engines with oxidation catalyst and particulate filter technology for the reduction of particulate matter (PM), hydrocarbons (HC) and carbon monoxide (CO) emissions has become an established practice. The design and performance of such systems have been commercially proven to the point that the application of these technologies is a cost effective means for states to effectively meet pollution reduction goals. One of the reasons that these technologies are so widely applied is because they can be sized and fitted based on easily measurable vehicle parameters and published engine emission information. These devices generally work passively with basic temperature and back pressure monitoring devices being used to alert the operator to upset conditions. The application of an effective NOx reduction technology in similar retrofit installation, is more complicated. There are no passive NOx reduction technologies that can be retrofit onto HDD vehicles.

Superchargers are engine driven positive displacement devices which increase the air mass flow into the engine, thereby leading to a better combustion efficiency. This gives an advantage of extracting more power from the same engine [1], thereby reducing emissions and achieving a better fuel economy [2]. With emission norms getting more and more stringent, the need for boosting engine intake air becomes very important [3]. There are many types of superchargers based on design [4], out of which, the roots-type positive displacement supercharger, is discussed in here. A 1-dimensional model of supercharger gives flexibility of choosing the right aspect ratio (length to the diameter of the rotor), deciding on the clearances (a tradeoff between volumetric efficiency and manufacturing capabilities) and arriving at the inlet and discharge port dimensions.

The correct timing of the diesel injection pump on engine is of major importance for all functions of the engine and for its exhaust emissions, during production pass off as well as in the field. Within the diesel service workshops a variety of devices exist to test the timing of the injection pump on engine. Most of them operate by clamp-on transducer being fitted to the injection pipe. A large uncertainty exists concerning the accuracy of such timing systems. Most diesel engine manufacturers do not have confidence in the timing devices capability and, therefore, do not recommend their usage. A working group within the International Organization for Standardization (ISO) adopted a method for the validation of these measurement systems, which usually is used to judge the capability of measurement gauges for industrial production processes.